1. Field of the Invention
The invention relates to a solder delivery system for terminating a plurality of closely spaced conductors.
2. Prior Art
In the past various systems have been developed for simultaneously delivering solder to a number of closely spaced contacts. As the size of electronic devices decreases and the density of component packing increases, the problems of delivery and of bridging the solder between contacts become significant.
U.S. Pat. No. 3,750,252 to Landman discloses the use of a single, continuous piece of solder to simultaneously solder a large number of terminals. The solder wire extends along a terminal strip, and upon heating the solder melts and coalesces on the individual contacts to form independent soldered connections. Unfortunately, a special terminal strip must be provided for each particular set of terminals.
U.S. Pat. No. 3,396,894 to Ellis discloses a plurality of bodies of solder disposed in heat-recoverable cups formed on a sheet of material. When heat is applied to the cups, they recover, the fusible melts, and the recovering cup material forces the solder out into contact with the objects to be soldered. Unfortunately, the size and exact position of the cups must be predetermined since matching the contacts and aligning the sheet with regard to the contacts is critical. In addition, recovery of the sheet can expel solder prematurely, that is, before the object to be soldered has reached the proper temperature to receive the solder.
U.S. Pat. No. 3,719,981 to Steitz discloses a method of applying solder balls which are appropriately spaced on the tacky surface of a pressure sensitized tape. Again, the product is limited by the size and spacing of the solder balls as well as by the requirements for precise alignment of the product.
U.S. Pat. No. 4,712,721 to Noel et al. similarly discloses mechanical means and methods for delivery of solder preforms of various configurations arranged in a myriad of configurations. These devices are similarly limited in application to specific predetermined contact patterns and require precise alignment for functionality.
U.S. Pat. No. 4,354,629 to Grassauer et al. discloses a solder delivery system having a continuous element of solder material disposed between polymeric layers, one of which is provided with window means to control the flow of solder. Although the use of a continuous solder element similar to that disclosed in U.S. Pat. No. 3,750,252 to Landman discussed above has certain advantages in the manufacturing of the solder delivery system itself, nonetheless, the system is likewise limited by its predetermined window size and spacing and by the precision of alignment required for the system.
U.S. Pat. No. 3,750,265 to Cushman discloses a method of preforming a continuous strip of solder to a plurality of leads or terminals. The solder is predeformed to be thinner in cross-section in areas between the terminals so that the solder is drawn to the terminals upon application of heat due to the surface tension effect. Unfortunately, the exact spacing of the terminals must be predetermined, and, again, alignment of the preformed solder is critical.
U.S. Pat. No. 3,464,617 to Raynes et al. discloses a length of adhesive coated tape and a length of solder secured to the tape by the adhesive. The tape and solder are used to sweat solder a pipe and fitting together by wrapping the two about the pipe so as to form the solder into an encircling ring around the pipe. The article disclosed contemplates a one-on-one application of the solder to a joint. Unfortunately, it does not contemplate the division of the continuous solder element among a plurality of electrical contacts.
In view of the prior art, it would be advantageous to have a solder delivery system that could be used with a variety of heating methods for simultaneously soldering a plurality of terminations of varying size and spacing wherein alignment of the system is not critical.